The treatment method that uses the percutaneous intervention technology to treat diseases is being used in more and more application fields. The catheter intervention treatment method can be used to place various kinds of materials, devices, and medicines in the heart, arteries and veins of the human body. For example, atrial septal defect (ASD) occluder, ventricular septal defect (VSD) occluder, patent ductus arteriosus (PDA) occluder, and patent foramen ovale (PFO) occluder, and the like can all be placed in the defective part of the heart via catheter to treat congenital heart disease.
When these devices are placed in the heart, arteries and veins of the human body using the catheter intervention method, since the heart, arteries, and veins of the human body have complicated anatomical structures, it is necessary to use a catheter, guide wire, and pusher in order to guarantee that the devices arrive at the predetermined parts. The catheter first arrives at the predetermined part under the guidance of the guide wire. When conducting this kind of surgery, it is necessary to use a very small and flexible catheter. Meanwhile, the catheter and the guide wire should be designed to have very good development under X-ray. When the catheter reaches the predetermined part, the guide wire is removed, and the device is included in the catheter and is pushed by a pusher to the end of the catheter via the channel established by the catheter. When the device reaches the end of the catheter, the device is released from the catheter. Finally, the device is broken off from the pusher.
The method that is normally used is to adopt threaded connection between the device and the pusher. After the pusher sends the device to the predetermined part, the thread is disengaged to break off the connection between the device and the pusher. This type of threaded connection can realize reliable connection between the device and the pusher and can realize controlled release at the same time. If the size of the device is selected inappropriately or the device is poorly expanded, the device can be included into the transportation catheter again, placed again, and finally released reliably. Under some circumstances, the device can also be removed from the human body via the catheter and replaced with a new appropriate device to be placed again.
This type of threaded connection method has a lot of limitations. The threaded connection is a hard connection. The degree of freedom of the device in the radial direction will be hindered before the device is released. As a result, the device is unable to adapt well to the anatomical structure of the predetermined part, and the doctor is unable to evaluate well the effect after the device is implanted (such as the occluding effect of an occluder). When a threaded connection is adopted, it is necessary to form threads on the device to be implanted. It is usually necessary to use a certain amount of metal material to form this part. As a result, the amount of the metal implanted into the human body is increased. The metal material used for the threaded connection part is usually different from the metal material used for the main body of the device. As a result, electrochemical corrosion occurs over the long term between the different metal parts of the implanted device, which shortens the safe service life of the device and increases the patient's long-term risk. The threaded connection needs a sufficient number of spirals in order to guarantee reliability. Therefore, it is necessary to rotate the pusher many rounds in order to disengage the connection. This requires a relatively long time during the operation conducted by the doctor. As a result, the surgical risk is increased.